Integrated circuits have traditionally been formed on bulk semiconductor substrates. In recent years, semiconductor-on-insulator (SOI) substrates have emerged as an alternative to bulk semiconductor substrates. An SOI substrate comprises a handle substrate, an insulator layer overlying the handle substrate, and a device layer overlying the insulator layer. Among other things, an SOI substrate leads to reduced parasitic capacitance, reduced leakage current, reduced latch up, and improved semiconductor device performance.